Molded bodies of a seal material to be used in devices which are used under circumstances such as a plasma atmosphere and a chemical atmosphere are required to have high stability against various chemical species, and molded bodies made of a fluorine based elastomer are chiefly employed (see, for example, Patent Document 1). In these devices, in recent years, gases, chemical liquids, and the like with high concentration and high chemical reactivity have been used for the purposes of improving efficiency, etc. However, in molded bodies made of a fluorine based elastomer which have hitherto been widely used, there is encountered such a problem that deterioration is so vigorous that they are no longer useful.
Of fluorine based elastomers, since perfluoroelastomers exhibit especially excellent plasma resistance and chemical resistance, they are frequently used in devices to be used under the foregoing severe circumstances (see, for example, Patent Document 2). However, the perfluoroelastomers are low in hot strength so that there is some possibility that inconveniences such as cutting of an O-ring molded body during the high-temperature treatment are generated.
Patent Document 1: JP-A-2000-119468
Patent Document 2: JP-A-2000-044930